From 4026f89d19394ea6819fd263ebd81425ae8247bb Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Fri, 2 Nov 2018 18:07:11 -0700
Subject: [PATCH] Fixed bug 4308 - Prebuilt SDL.dll files not compiled with
 ASLR support (DYNAMICBASE)

Cameron Gutman

The current SDL 2.0.8 and the prerelease SDL 2.0.9 are compiled without the DYNAMICBASE flag to indicate that ASLR may relocate the DLL at load-time. https://docs.microsoft.com/en-us/cpp/build/reference/dynamicbase-use-address-space-layout-randomization?view=vs-2017

When I build SDL.dll myself using the VS2010 project, the DLL has the DYNAMICBASE flag set (as is the default). Similarly, MinGW-w64 also enables ASLR by default on all binaries for a couple years now (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=836365)
---
 configure    | 102 +++++++++++++++++++++++++++++++++++++++++++++++++++
 configure.in |  51 ++++++++++++++++++++++++++
 2 files changed, 153 insertions(+)

diff --git a/configure b/configure
index aee0cb6ec..db15105e9 100755
--- a/configure
+++ b/configure
@@ -16063,6 +16063,108 @@ esac
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_no_undefined" >&5
 $as_echo "$have_no_undefined" >&6; }
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker option --dynamicbase" >&5
+$as_echo_n "checking for linker option --dynamicbase... " >&6; }
+have_dynamicbase=no
+case "$host" in
+    *)
+        save_LDFLAGS="$LDFLAGS"
+        LDFLAGS="$LDFLAGS -Wl,--dynamicbase"
+        cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+
+int
+main ()
+{
+
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+
+        have_dynamicbase=yes
+        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--dynamicbase"
+
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+        LDFLAGS="$save_LDFLAGS"
+        ;;
+esac
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_dynamicbase" >&5
+$as_echo "$have_dynamicbase" >&6; }
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker option --nxcompat" >&5
+$as_echo_n "checking for linker option --nxcompat... " >&6; }
+have_nxcompat=no
+case "$host" in
+    *)
+        save_LDFLAGS="$LDFLAGS"
+        LDFLAGS="$LDFLAGS -Wl,--nxcompat"
+        cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+
+int
+main ()
+{
+
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+
+        have_nxcompat=yes
+        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--nxcompat"
+
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+        LDFLAGS="$save_LDFLAGS"
+        ;;
+esac
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_nxcompat" >&5
+$as_echo "$have_nxcompat" >&6; }
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker option --high-entropy-va" >&5
+$as_echo_n "checking for linker option --high-entropy-va... " >&6; }
+have_high_entropy_va=no
+case "$host" in
+    *)
+        save_LDFLAGS="$LDFLAGS"
+        LDFLAGS="$LDFLAGS -Wl,--high-entropy-va"
+        cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+
+int
+main ()
+{
+
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+
+        have_high_entropy_va=yes
+        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--high-entropy-va"
+
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+        LDFLAGS="$save_LDFLAGS"
+        ;;
+esac
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_high_entropy_va" >&5
+$as_echo "$have_high_entropy_va" >&6; }
+
 # Check whether --enable-libc was given.
 if test "${enable_libc+set}" = set; then :
   enableval=$enable_libc;
diff --git a/configure.in b/configure.in
index ae866ff0c..91b45d304 100644
--- a/configure.in
+++ b/configure.in
@@ -232,6 +232,57 @@ case "$host" in
 esac
 AC_MSG_RESULT($have_no_undefined)
 
+AC_MSG_CHECKING(for linker option --dynamicbase)
+have_dynamicbase=no
+case "$host" in
+    *)
+        save_LDFLAGS="$LDFLAGS"
+        LDFLAGS="$LDFLAGS -Wl,--dynamicbase"
+        AC_TRY_LINK([
+        ],[
+        ],[
+        have_dynamicbase=yes
+        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--dynamicbase"
+        ])
+        LDFLAGS="$save_LDFLAGS"
+        ;;
+esac
+AC_MSG_RESULT($have_dynamicbase)
+
+AC_MSG_CHECKING(for linker option --nxcompat)
+have_nxcompat=no
+case "$host" in
+    *)
+        save_LDFLAGS="$LDFLAGS"
+        LDFLAGS="$LDFLAGS -Wl,--nxcompat"
+        AC_TRY_LINK([
+        ],[
+        ],[
+        have_nxcompat=yes
+        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--nxcompat"
+        ])
+        LDFLAGS="$save_LDFLAGS"
+        ;;
+esac
+AC_MSG_RESULT($have_nxcompat)
+
+AC_MSG_CHECKING(for linker option --high-entropy-va)
+have_high_entropy_va=no
+case "$host" in
+    *)
+        save_LDFLAGS="$LDFLAGS"
+        LDFLAGS="$LDFLAGS -Wl,--high-entropy-va"
+        AC_TRY_LINK([
+        ],[
+        ],[
+        have_high_entropy_va=yes
+        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--high-entropy-va"
+        ])
+        LDFLAGS="$save_LDFLAGS"
+        ;;
+esac
+AC_MSG_RESULT($have_high_entropy_va)
+
 dnl See whether we are allowed to use the system C library
 AC_ARG_ENABLE(libc,
 AC_HELP_STRING([--enable-libc], [Use the system C library [[default=yes]]]),